Context

I have a web game in JavaScript.

I send scores and achievements with AJAX during the game.

So anyone can view the source code, copy this request and cheat on my game.

Questions

Any idea of how prevent this?
With a token from server (I never used this system)?

Code

jquery:

$.post('ajax/score.php', {pseudo: $pseudo, score: $score, achiev: $achiev},
    function(data) {
        $('#loader').show().delay(3000).fadeOut(1000);
    }
);

php:

if (isset($_POST['pseudo']) &&
    isset($_POST['score']) && 
    isset($_POST['achiev'])) {
    ...
}

回答1:

As the game is client side, there is no way to ensure that they do not "cheat". There are ways to make it more difficult.

Have all calculations performed serverside, and send back tokens...this may not be possible/feasible for your game.
Change the code served each time so that it will require more time to "decipher" all the requests.
Obfuscate the code...this is only a deterrent.
Have "tokens" sent during the game to see if the data matches (for example you can't win the racing game in 5 sec)...this too can be spoofed.

As long as the game is client side, it cannot be "secured".